Sensing systems are employed for a wide variety of purposes. Sensing systems may detect motion of an object or environmental conditions, for example. Sensing applications are applicable to many industries such as medical, processing, transportation, and aeronautics industries, among others. Because of the diversity in purpose for sensing systems, many considerations must be considered by engineers when designing a new sensing system. Considerations such as cost, precision, measurement range, durability, maintenance, and even physical characteristics are generally considered by engineers.
Non-contact sensing systems are sensing systems that, unlike contact sensing systems, do not require a sensor to physically contact an object being measured. Non-contact sensing systems offer many advantages over contact sensing systems, such as the ability to provide information regarding an object and/or condition of interest without expensive and invasive sensor mounting assemblies. Non-contact systems, unlike contact systems, are also advantageous because they do not impact the system they measure. Radar systems include one example of a non-invasive sensing system. Radar systems use transmitted and reflected radio waves, typically on the order of 0.9-100 GHz, to determine the presence, location, and/or speed of objects. Some radar systems operate by transmitting either a constant continuous wave (CW) signal or a pulsed signal. Most CW radar systems operate under the principle of the Doppler effect, in which the change in reflected signal phase and/or frequency with respect to a transmitted signal phase and frequency is measured. CW radar systems that rely on the Doppler effect provide a mechanism of detecting a moving object by transmitting microwaves at a targeted object and detecting the change in frequency and/or phase of microwave signals reflected from the object.
Further, non-contact radar techniques provide a sensing mechanism that is relatively unaffected by temperature, dust, debris, water, and many other obscurants when the proper transmit frequencies are used. Radar sensing systems may accurately provide information on the speed, location, and direction of movement of targets being sensed, as compared to other less-accurate sensing systems. One need in aeronautics or power generation applications, for example, would be to determine accurately the speed of a turbine engine and, particularly, the speed of one or more bladed rotors in a turbine engine.
In this context, the present invention is directed to addressing deficiencies of conventional measurement systems with systems and methods for accurately sensing the speed of a moving object such as a bladed rotor of a turbine engine.